Fuel cell power plant systems which utilize water as a coolant will preferably be fitted with a closed water circulating and recirculating system which does not require substantial, if any, amounts of make up water. It is greatly preferred to replace any water which is used by the system with product water formed by the electrochemical reaction of the fuel cells. In fuel cell power plants which utilize a raw hydrocarbon fuel such as methane, naphtha or the like, which must be reformed to a hydrogen rich fuel gas in a catalytic reformer, varying amounts of ammonia will be formed in the reformer and thus will be present in the reformer effluent, i.e., in the hydrogen rich fuel gas. Depending on the amount of nitrogen present in the raw hydrocarbon gas being reformed, the amounts of ammonia present in the reformer effluent can be as high as about 500 ppm by volume. The ammonia levels in the fuel gas must be lowered to a level of not more than about 2 ppm by volume before the fuel gas is fed into the cells because the ammonia will poison the catalysts in the cells if present in higher concentrations. To remove the ammonia from the fuel gas, the reformer effluent is fed into a cooler housing through which it rises to an outlet at the top of the housing which leads to the power section. The effluent gases entering the bottom of the coolant housing are at a temperature of about 415.degree. F. Water, at a temperature of about 130.degree. F. is admitted to the top of the housing in a spray, so that the water is sprayed into, and falls through the rising reformer effluent gases. The temperature of the reformer effluent gases is thus lowered to about 140.degree. F. as the gases leave the cooler, and the ammonia and other contaminant gases, such as carbon dioxide, are stripped out of the reformer effluent by the counter flowing water. The concentrations of ammonia in the fuel gas going to the power section from the cooler will be about 2 ppm by volume, or lower. The water which settles in the bottom of the cooler, which has entrained therein ammonia and other gaseous contaminants, is withdrawn from the cooler. The contaminated water will be at a temperature of about 255.degree. F. and a pressure between 140 to 160 psia. This water can contain up to about 400 ppm by weight ammonia, in various forms, such as free ammonia, ammonium ions, and in various ammonium carbonate and bicarbonate compounds. This ammonia can be removed from the water with the normal ion exchange water purification system used in the power plant, however, this would require frequent regeneration of the purification system, which would also result in substantial amounts of water being removed from the power plant as waste water. As noted above, the power plant is designed to be a nonuser of make up water, thus the use of the ion exchange beds to rid the water of these large amounts of ammonia is not acceptable.